Virtual syringe lets surgeons practise piercing skin and muscle

As my syringe presses against the skin and muscle surrounding a patient’s knee joint, I feel a brief resistance. A gentle increase in pressure, though, and the needle pops through, ready to inject the drug. But this isn’t a real patient or syringe – they’re both virtual.

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“It stays exactly where you inject it, so you need to put it in the right places,” says FundamentalVR co-founder Richard Vincent. “That’s what this system teaches them to do.”

In the coming months, the simulation will be used in US hospitals by surgeons training to administer the drug during knee replacement surgery. This requires about 20 injections at six different stages.

The system runs on off-the-shelf equipment, which means it is more affordable than existing surgical simulators that require bespoke machines, such as those used to practise keyhole surgery. The company claims all the necessary hardware can be bought for less than £5000.

The simulated procedure is designed to work with a readily available high-end computer and an HTC Vive headset. Motors in the stylus exert increasing resistance when the virtual syringe pushes against skin, muscle and bone.

Seeing a syringe

The stylus doesn’t look or feel like a syringe outside of the simulation, but that soon changes when you’re immersed, says the company’s other co-founder Chris Scattergood. “We suddenly realised that when you’re in the VR, you might be holding it like a pen but you believe you’re holding a syringe – you’re seeing a syringe doing syringe stuff.”

There are two buttons on the side of the stylus, one to inject the virtual drug and the other to withdraw the needle. The system knows the ideal injection pattern for the drug and gives surgeons a score based on how accurately they have administered it. A visual map shows how close they came to a perfect result.

The company also plans to make other simulations to teach a range of surgical techniques using the same hardware.

“In surgery, you can often feel things before you can see them,” says Stan Dysart, a surgeon at Pinnacle Orthopaedics in Marietta, Georgia, who advised on the design of the system.

Shafi Ahmed, a surgeon at the Royal London Hospital, has also tried it. “It works very well, it’s a nice model, very elegant,” he says. “It demonstrates the value of virtual reality in training.”

In the future, says Ahmed, surgeons may benefit from more sophisticated haptic feedback that can deliver the sensation of temperature as well, for example. More realistic graphics could also help to heighten the sense of immersion.